Answer:
A. E(x) = 1/n×n(n+1)/2
B. E(x²) = 1/n
Step-by-step explanation:
The n candidates for a job have been ranked 1,2,3....n. Let x be the rank of a randomly selected candidate. Therefore, the PMF of X is given as
P(x) = {1/n, x = 1,2...n}
Therefore,
Expectation of X
E(x) = summation {xP(×)}
= summation {X×1/n}
= 1/n summation{x}
= 1/n×n(n+1)/2
= n+1/2
Thus, E(x) = 1/n×n(n+1)/2
Value of E(x²)
E(x²) = summation {x²P(×)}
= summation{x²×1/n}
= 1/n
Answer:
The principal must be = $8991.88
Step-by-step explanation:
Formula for compound interest is:

Where A is the amount after 't' years.
P is the principal amount
n is the number of times interest is compounded each year.
r is the rate of interest.
Here, we are given that:
Amount, A = $15000
Rate of interest = 13 % compounded quarterly i.e. 4 times every year
Number of times, interest is compounded each year, n = 4
Time, t = 4 years.
To find, Principal P = ?
Putting all the given values in the formula to find P.

So, <em>the principal must be = $8991.88</em>
The ad cost for half page Saturday after discount is
15% of 380 = 0.15×380 = 57
380 - 57 = 323
The ad cost for half page Tuesday after discount is
15% of 330 = 0.15×330 = 49.5
330 - 49.5 = 280.5
Cost of the ads for 10 Saturdays and 10 Tuesdays
(10×323)+(10×280.5) = 3230+2805 = 6035
The correct answer is y=1/2x-3